I will talk to my sister the hotel expert about group rates, but in the meantime, there's a Super 8 just behind Bally's on the strip that's pretty darn affordable, and it's a good location to boot. I've stayed there more than once. It's not posh, but for a shower, crash space, and a place to leave your stuff it's fine.
http://www.super8vegas.com/
Official Super 8 site
We're talking (as of today) with a AAA discount: $80/night for 3 nights, 2 people, 2 queen beds.
I'd personally recommend not going the group rate route for hotels, as people's schedules change all the time, and if enough people cancel at the last minute, someone may be left holding the bag.
The key to getting rooms (and cheap rooms) in Vegas is to BOOK EARLY and garauntee with a cc. It's way better to lock in a room now (*especially for a holiday weekend*) and then continue to search for better deals/other locations. You usually can cancel up to just 24 hours before your reservation (verify that when you book the initial room).
Listen to my voice, peoples.